The endotracheal intubation is a commonly used procedure during which a semi rigid plastic tube, called endotracheal tube, is inserted into a patient's trachea through the open mouth. Frequently a laryngoscope is used to view the throat area while the tip of the endotracheal tube advances toward the vocal cords. This procedure is not a trivial one especially in the inconvenience of emergency situations and with the patients having various irregularities and complications in the throat and neck areas. During the last five to ten years many researches and physicians advocated use of endoscopes during the intubation procedures. The tip of the flexible shaft of an endoscope is inserted into the endotracheal tube and temporarily secured near the distal end of it. Depending on the type of an endoscope used, a practitioner performing intubation can see the area in the immediate vicinity of the distal end of he endotracheal tube either on the video screen of a monitor or looking in the ocular of a simpler endoscope. It is quite obvious that such use of an endoscope reduces number of traumas and helps to ease and speed up the intubation process. Many existing endoscopes can be used for such application. However, a typical medical endoscope is an expensive and bulky instrument, utilizing powerful light sources and fiber optic bundles for delivery of light and/or images. There is a need for a portable and inexpensive endoscope suitable for use in the operating rooms as well as, emergency situations, and anywhere an endotracheal intubation needs to be performed. The attempts to develop a portable and less expensive endoscopes, particularly convenient for endotracheal intubation have been made. The U.S. Pat. Nos. 7,042,487 and 6,929,600 teach how to make a less bulky and less expensive endoscopes yet they failed to get rid of fiber optic bundles and external light sources. This invention discloses the way to do just that, how to construct a low cost and portable endoscope that can be conveniently used for endotracheal intubation in any situation.
The endoscopes have been useful tools in the medical field for many decades. Doctors and paramedics use them for diagnostic purposes as well as in combination with the surgical tools during operations. There are endoscopes that combine imaging functions with the tubular channels for moving liquids and gases in and out of body and channels for controlling the surgical tools. In spite of being well known tool, the endoscopes find new useful applications. One of such relatively new applications is providing assistance during intubation procedure. Benefits of the endoscopes during intubation have been demonstrated in the scientific medical publications during the last 5-10 years. The endoscopes currently known are rather bulky and expensive. High price, a suitcase-type dimensions at best, and large power requirements preclude use of the endoscopes in the battlefield and the every day typical ambulance situations. There is a need for a low cost, small, light weight endoscope that medical personal can use equally well in the traffic accidents on the streets and in the operating rooms.
The main function of an endoscope is to make available to a person a viewable image of the scene located in front of the inserted probe end of the flexible shaft. This can be accomplished in one of two ways. First, traditional way offers a solution through the use of a coherent bundle of light-conducting fibers combined with the image projecting lenses. The fibers bring forward the image of the scene, which is illuminated by the light brought by a few insulated fibers inside of the body from the powerful external light source. This image then either viewed by the eye through an eyepiece lens or projected on a TV camera and viewed from the TV monitor. This concept results in an endoscope system that is complicated, expensive and bulky. The typical light source is a halogen or an arc lamp of 50 to 75 watts.
Conventionally, many fibers bundled together with a charge couple device (CCD) used to take pictures to form an endoscope, which is used to penetrate hollow organs (e.g., stomach, large intestine and trachea) to get tissue images for determining the type and development degree of diseases. Light from a light source is transmitted through the fibers to illuminate a tissue of the human body. The reflected light is transmitted back via the fibers to the CCD for formation of an image displayed on a screen. The diameter of common fibers is smaller than 100 microns. In order to observe an image region from several millimeters to several centimeters, it is necessary to bundle a considerable number of fibers to obtain an image with a sufficient resolution. Moreover, the size of a typical CCD image sensor is generally large. The above fiber-type endoscope has the disadvantages of high price and complexity and difficult assembly and maintenance. Because, the above fiber-type endoscope has a high price, it is usually used repetitively for many times so that infection may occur due to difficult sterilization.
In order to solve the above problems of the fiber-type endoscope, U.S. Pat. No. 6,387,043 discloses a transmission type endoscope, wherein a complementary metal-oxide semiconductor (CMOS) image sensor replaces the CCD. A transmission type endoscope applies to common surgical laporoscopic operations. The transmission type endoscope comprises a penetrating member, a hollow portal sleeve connected with the penetrating member, and a main body at the rear end. A penetrating member has a sharp front end for penetrating tissues. This penetrating member is equipped with two imaging CMOS cameras, one inside the member and another outside of it. Each of these cameras has and LED light source for illumination, object lens for projecting images, and CMOS image sensors for converting optical signals into electric signals.
U.S. application Ser. No. 2002/0080248 A1 discloses an endoscope of another type. Light from the light source and reflected light present via fibers in conventional endoscopes. In this disclosure, the illumination way of the light source is reserved. Only the CCD image sensor is replaced with a CMOS image sensor. This endoscope comprises a flexible sleeve, a handle, and a control box. An optical imaging device is installed at the front end of the flexible sleeve. The optical imaging device comprises from outside to inside an outer cover, optical fibers, and an image sensing device. An optical lens is disposed at the front end of the image sensing device. A CMOS sensor is disposed behind the image sensing device. The CMOS sensor can be a circular or a square image sensor. The handle is used for convenient maneuvering of the endoscope. The control box provides electric power and has an image processing board for processing image signals.
Although the above two disclosures address the problems of fiber-type endoscopes and avoid the situation of using too many fibers, there remains a need to further develop a solid state image sensor with a small size and low power requirement.
The other, more feasible, method constructs an endoscope with an image sensor placed near the front end of the flexible probe. This is possible because the solid state image sensors are becoming available in sufficiently small packages. Having an image sensor at the front end eliminates or reduces the signal losses and simplifies construction. The availability of small size and high efficiency white light emitting diodes (LED) in combination with high sensitivity image sensors allows construction of a simple and elegant endoscope system, such as described in US Application Publication 2006/0004258, by Wei-Zen Sun, et al. In this publication a CMOS image sensor is installed behind the light emission devices. Light reflected by the human body is focused by an object lens onto the CMOS image sensor, which converts the optical signal into an electric signal. The electric signal is processed by the image sensor drive circuit board, which is positioned immediately behind the image sensor, and is then sent to the display device via electric wires for real-time monitoring of images of the human body tissue. The lens has a very restricted view angle due to the obstruction of the multiple LED illuminator board positioned in front of the lens. The lens can see the space in front of it through the small aperture made in the center of the housing integrated with the light source module. The necessity of the drive circuit board and multi-LED illuminator module prohibit construction of a small diameter endoscope probe.
Thus, there remains a need for further improvements in portable endoscopes in the use.